Production of lubricating oils



United States Patent O PRODUCTION OF LUBRICATING OILS Robert A. Macke and Edward F. Wadley, Baytown, Tex., assignors, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware This invention concerns a novel process for producing lubricating oils of particularly high quality. The invention comprises 4a combination process for upgrading lubricating oil components of refinery stocks. In particular the invention'concerns production of high viscosity index lubricating oils from parainic base crude oils and from cycle stocks resulting from the catalytic cracking of petroleum oils. It is the particular feature of this invention to produce lubricating oils by the solvent extraction of a mixture of catalytic cycle stock and parainic lubricant fractions. This process is particularly attractive in maximizing the yield of high quality lubricating oil from 'these lubricant sources.

As is generally known, an important criterion of a lubricating oil relates to the viscosity characteristicsl of the oil. For many applications, temperatures at which a lubricant must be employed are several hundred degrees Fahrenheit abovetemperatures existent prior to usey of the lubricated mechanism. Consequently, it becomes a realprobleni to provide lubricating oils having the proper viscosity over the entire operating temperature range due to the. decrease in viscosity of a lubricating oil as the oil becomes heated. This characteristic of a lubricating oil is generally identilied as the viscosity index of the oil andessentially` provides information as to the change in rviscosity of the oil over the temperature rangel of 1`00 to 210 F. The higher the viscosity index, the smaller the change in viscosity with temperature. ,It is apparent that for many applications itis desirable to employ lubricating oils'having the highest possible viscosityv index.

Production of high viscosity index lubricating oils can most readily be achieved by producing such lubricating oils from paraiiinic base crude petroleums. Of all hydro- `carbon types, parafnic hydrocarbons have the highest .viscosity indices falling in the range of about 125V to 180.

Consequently, when the lubricating oil fraction is segregated from a paraflinic base'crude oil it is relatively easy to process this fraction to obtain a final lubricating oil product having a high viscosityl index. For example, the lubricating oil fraction of a parafnic base crudeoil can be treated with a selective solvent for aromatic hydrocarbons so as to provide a rainate product of high visf cosity index` in relatively large yields. Parainicbase crude oils particularly attractive for production of lu- 2,780,581 Patented Feb. 5, 1957 2 bricating oils include Panhandle, Ellenberger, New Hope, and Mid-Continent petroleums.

However, truly paratrinic lube crude oils are unusual at the present time, and the supply of such oils is limited. The need, therefore, exists for extending available sources of feedstock for producing high viscosity index lubricating oils. l

It has recently been found that high viscosity lubricating oils can be derived by processing steps applied to mixed base crude oils. In accordance with the technique referred to, a gas oil fraction is segregated from a mixed base crude oil and subjected to a catalytic cracking operation. Thereafter the products of catalytic cracking, or that fraction of the products boiling in the lubricating oil boiling range, are subjected to solvent extraction inorder to recover la raflinate product rich in paranic materials and constituting a good lubricating oil base,A stock. The

process of producing lubricating oils from the products of a catalytic cracking process in this manner is lspecifically disclosed and claimed in United States Patent 2,660,552, issued November 24, 1953, to Forrest H. Blending.

While the recovery of lubricating oils from catalytically cracked products is a particularly desirable and attractive process, the process is characterized by one disadvantage. Thisis the fact that relatively low yields of high quality lubricating oil are obtained bythe selective solvent extraction operation as compared to the yields which can be obtained by selective solvent extraction of paraflinic base lubricating oil distillates. For example, under comparable conditions, solventV extractionV of a Panhandle lubricating oil distillate can be carried out to provideV a yield of lubricating oil of about 62 to 69%, While recovery of a similar quality lubricating oil from catalytically cracked products can only be achieved at yields of about 37 to Of equal importance is the fact that larger amounts of solvent must be used when extracting catalytically cracked products as shown by a lower raffinate productivity factor which Will be defined subsequently. It `is 'apparent from this that lubricating oilsscan only be produced from catalytically cracked products in existing lubricant plants by loss in yield of the iinal lubricant product as compared to operation of the plant when employing a parainic base lubricating oil.

It i's the particular object of this invention to provide a -process'for solvent extracting catalytically cracked products in order to obtain lubricating oils at higher yields for a given solvent extraction capacity and treat than heretofore'obtainable. The process of this inventiony is based on the unexpected discovery that marked .processing advantages are obtained by extracting mixtures of the lubricating oil fractions derived from cycle stock and derived from parafnic base crude oils.

The nature of this process can be understood by reference to the accompanying drawing which diagrammatioally illustrates a preferred embodiment of the present invention. Y

In accordance with the invention a paratiinic base crude oil is brought into a distillation zone 2 through line. 3.

The distillation operation may be conducted to permit removal of light petroleum fractions through lines 4, 5, 6, and 7 and a lubricating oil fraction through line 8. Residual fractions of the petroleum oil `may be removed as a bottoms product through line 9. While distillation zone 2 is shown as a single zone, it is understood that it may comprise a plurality of zones operating at diierent pressures if desired.

The waxy lubricating oil fraction withdrawn from still 2 through line 8 will constitute a portion of the original crude oil and will boil within the range of about 650 to 1100 F. It will normally have a dewaxed viscosity index of about 70 to 90. In the practice of this invention this lubricating oil fraction is processed in combination with a cycle oil derived from a catalytic cracking operation as indicated in the lower portion of the drawing.

A crude petroleumwoil such as a mixed base crude oil is #introduced lt'o `distillation Zone through li'ne "11. The distillation operation may be ycor'iducte'd to -permit lremval *of volatile fractions overhead through li'ne 13 Aand fof heavier :boiling products such as gasoline, kero- -lsene :anda-eating cils 'through side stream withdrawals 114,

`15, 'and 16. -A heavy yboiling frfa'c'ti'on boiling within the range of about 6750 to 1100" F. may be withdrawn through line 17, with residual'p'ortions of th'e crude oil Ibeing fwithdrawn trom-still 10 thr'ough line 18. The fracftionlof s'tream 317 constitutes a gas -oil which is subjected to catalytic cracking 'in zione A1'9. Y

The cracking operation tob'e carried fout in 'zone 1'9 may I-befcvif 'any desi-red type. The catalyst employed-may bc a-modiiied naturalfor synthetic clay or may 'constitute 'a gel -typ'e of "catalyst. fExamples of these 'are fmontmorillonite clays, silica-alumina, silica-magnesia 'composites or other conventional cracking catalysts. The opera'tio'n may be 4of a continuous 'or batch nature employingxed beds, -moving beds, fluidized, or 'suspens'oid systems. The heat lrequired Vfor cracking may be supplied as preheat of yprocessed materials and/or as'the 'sensible heat of 'exoth'ermically regenerated catalyst or in 'anyother conventional manner. The cracking is carried out-at temperatures ofabout 800 to 1000 F. andpressures of 'about atmospheric vto 25 p. vs. i. g. or `hi'gher'in Aa 'manner which is 'well known.

The total cracked products are removed from crack- Fractionator 21 may be op- Y may'iin'clude all portions ofthe catalyticall y cracked -products boiling above about V650" 1F. and inthe event the cracking operation =was of a fluidized nature 'this prod- -uctfmay includev a :small-amount of vvcatalyst particles icar- `1`ied`=overfrom-the catalytic crackingzone. -ln'thi-scase "it is 'n'ece'ssary topass the product stream of-lin`e26 to v, fn sc'p'aration -lzon'e 27 permitting separationfof catalyst .particles from the lhydrocarbon product stream. Zone 27-may vconstitute altration -zone'or other means to separate the catalyst. The clarified product withdrawn from Vseparationfzone 27-is commonly called-clarified oil -or-cycle oil. -As` used-.herein either of these terms isemploycd to .identify the fraction vof fcatalyticall-y cracked `products boiling within .the range `of about 650 to and solvent is then heated suiciently to secure the solution of all wax present. Thereafter, the mixture of oil and solvent is cooled to a temperature of about 25 F. to 50 F. so as to secure the crystallization of the wax present. The chilled mixture of oil, solvent and rwax is then filtered to eliminate this wax permitting removal from zone 30 through line 31 of a dewaxed hydrocarbon oil.

The dewaxed oil is then passed through line 31 to a solvent extraction zone 32 wherein the oil is subjected to contact with a solvent exerting a selective solvent action towards aromatic constituents. As is well known, a variety of solvents may be employed to secure the desired selective removal of aromatic constituents. Thus, for example, sulfur dioxide, phenol, furfural, nitrobenzene, and other solvents may be employed. While the contacting of the solvent and oil may be conducted in any desired contacting equipment of a batch or continuous nature, countercurrent treating technique of the nature illustrated is preferably employed. In this technique the oil feed of line 31 -is introduced yto a countercurrent treating tower 32 at a point near the bottom thereof. Tower 32 may be provided with packing, 'perforated plates or l'equivalent means tosecure 'effective liquid-liquidcontact.

A solvent Vsuch as phenol is brought into an 'upper ,portion of the tower through line 3?. The 'oil 'passes upwardly through the tower while the solvent Apasses vdownwardly through the tower permitting removal from the bottom of the tower 'of the extract phase which is removed through line 33a. The material withdrawn from the top of tower 32 through line 34 is .known as the rain'at'ephase and consists principally of vthe'initialoil 4'feed minus the major amount of the aromatic constituents originally present in the feed, admixe'd with small proportions of the solventemployed during 'the contacting.

The particular details relating to the solvent extraction 'step are 'nota'pa'rt of this invention an'd lit 'is 'to be understood that any desired refinements of solvent yextrac- 'tion 'operations may be used. For example, when employing .phenol as a solvent it is 'preferred to employ about 0 to A10% of water as a solvent modifier. Again, itis 'ordinarily preferred to maintain'a temperature gradi- "ent'along the solvent extraction "tower sothat the bottom of the tower will ordinarily be maintained at atempera- `ture of about to 2'50"F. while the top `of the tower will be 'maintained at a temperature of about 160 to 260 F. While the amount of solvent required will de p'c'ndup'on the properties of the oil feed and the 'desired vproperties of theraflina'te product, in general, about'lOO 'to 400% of 'solvent is employed, based on 'the oil feed.

The raffinate product of line 34 is preferably passed to `a 'final distillation zone 35 wherein residual solvent is 'driven overhead through line 36 while the 'final lubricatingoilproduct'is removed as a'bottomsproduct through line 37. It'willalso be understoodthattheilubeproduct 'of 1in'e'37 m'ayvbesubjected to other yfinishing 'operations Such as clayltreating or the like.

:In the vprocess particularly illustrated inthe drawing, it "was indicated that the cycle oil and virgin 'lube distillate were to be dewaxed prior to the solvent extraction operation. YThisis an optional Vfeature since,.if desired, the twodis'tillates can "rst be vsolvent extracted and r'the raffinate Lof-this operationcan be subjected to dewaxing.

-A ain, while the process illustrated applies `a dewaxing 'sieraden TABLE r 1o Phenol extracting Panhandle and cycle stack mixture of dewaxed 150 neutral 50% Pan- 15 Panhandle handle, Cycle 50% Cycle Stock Stock Charge Stock Source:

Gravity, API 27. 7 20. 4 12. 2 20 geen, F., COC 415 41o 415 100 F., SSU 203 251 412 210 F., SSU.. 45. 7 46.7 49.7 V. I 83 56 0 15 5 di ns Vol. Percent Phenol 175 141 140 25 Percent Water in Phenol 3. 0 3. 0 3 0 Percent Water Injected in Tower Botto 7 2 8 3 0 ez 51 a1 30 33.0 32. 9 32. 7 435 415 425 @100 F., SSU 400 726 1,700 210 F., SSU. 51.0 54. 7 62.5 V. I -50 -202 40 Productivity Factor Y/ T 0. 0. 36 0. 26

In the data presented in Table I, a factor called productivity factor or Y/ T is employed. In this expression 4- Y is the rainate yield and T is the phenol treat required so that this expression serves to correlate the yield of lubricating oil obtained with the treat of solvent required. With reference to the solvent extraction of the Panhandle neutral distillate by itself, it will be observed that a productivity factor of 0.35 was obtained, in order to obtain a lubricating oil product having a viscosity index of 113. For comparative purposes, however, it will be observed that in extracting the cycle stock neutral distillate, a productivity factor of only 0.26was obtainable producing a lubricating oil distillate having a viscosity index of 112. These data indicate that in the solvent extraction of lubricating oil feed stocks to provide lubricating oil having a viscosity index of about 112, a 35% greater Y/T is `obtained when employing 6() a Panhandle distillate feed stock as compared to the Y/ T of a cycle stock distillate feed stock. However, as shown in Table I, provided a mixture of 50% of each of these dewaxed distillates is employed, a lubricating oil product can be obtained having the same viscosity index at a G5 productivity factor substantially that when processing Panhandle distillate alone. Thus, in accordance with this invention it is possible to upgrade cycle stock to lubricating oil without the serious drop in yield-treat relationship which would ordinarily be sustained by extracting the cycle stock alone.

A second series of experiments were then conducted employing a somewhat heavier lubricating oil fraction of cycle stock and Panhandle crude oil. The complete data relating to these experiments are set forth in Table II:

Charge Stock Source:

Gravity, API 26. 2 16. 1 4. 8 lilash, F., GOC 455 450 480 F., SSU- 426 863 4,620 210 F SSU 57.1 66.1 97.7 l' ai it 1st our Treating'Oonditions: l

Vol. Percent Phenol 168 119 124 Percent Water in Phenol 3.0 3. 0 3. 0 Percent Water Injected in Tower Bottom u 2 8 2.9 2 9 219 192 175 R m t 210 166 a na e:

Yield, Vol. Percent 69 51 25 Gravity, API 30.8 30. 7 3l. 9 lgsh, F., COO 450 455 470 100 F., ssn 29s 299 292 210 F., SSU.- 53.3 53.5 53.8 V. I 1(1)? 11116 111 5 15 Extract:

Yield, Vol. Percent 31 49 75 Gravity, API 1,6. 7 3. 4 2. 5 glash, F., COC 0 455 475 100 F., SSU.. 1,669 V I@ 210 F., SSU 80 126.8 186 Prodcti'iit'yi'if/'TI .I 0.41 "fi' ""f These data again bear out the very real advantages obtainable by solvent extracting mixtures of paraflinic lubricating oil distillate stocks and such distillates derived from catalytically cracked products. The yield-treat relationship in extracting this mixture of virgin lube distillate and cycle oil lube distillate is shown to be substantially that obtainable when extracting a parainic lube distillate alone, and substantially double that obtainable when extracting cycle oil alone.

As described, therefore, this invention concerns a process for manufacturing lubricating oils by solvent extraction of a mixture of a virgin Ilubricating oil distillate and a catalytic cycle oil. In order to obtain the benefits of this invention it is essential that the virgin lubricating oil distillate be obtained from a parafnic base crude oil; such a distillate is particularly characterized by a viscosity index of about 70 to 90, based on the inspection of the dewaxed distillate. Substantially equal amounts ofthe cycle oil and virgin lubricating oil distillate are preferably employed. More broadly, however, the proportion of the cycle oil in the mixture may range from about 10% to 60%.

What is claimed is:

l. A combination process for producing lubricating oil comprising the steps of catalytically cracking a gas oil boiling within the range of about 650 to 1100" F., segregating a rst oil fraction boiling within the range of about 650 to 1100 F. from the cracked products, segregating asecond oil fraction boiling within the range of about 650" to 1100 F. from a paratlinic crude oil, and contacting a mixture of said iirst and second oil fractions with a selective solvent for aromatic compounds to remove aromatic compounds frorn the said mixture, said mixture containing about 50% olf said rst oil fraction, said process including the step of dewaxing said oil fractions.

2. A combination process for producing lubricating oil comprising the steps of catalytically cracking a gas oil boi-ling within the range of about 650 to 1100 F., segregating a iirst oil fraction boiling within the range of about 650 to 1100 F. from the cracked products, segregating `a second oil fraction boiling within the ran-ge of 7 about 650 to 1100" F. from a parainic crude oil, and contacting a mixture of said rst and second oil fractions with a selective solvent for aromatic compounds to remove aromatic compounds from the said mixture, said mixture containing about 10% to 60% of said first oil fraction, said process including the step of dewaxing said oil fractions.

References Cited in the tile of this patent UNITED STATES PATENTS Bahlke Oct. 15, 1935 Stratford Aug. 25, 1936 Wagner et al. Apr. 25, 1939 Dearborn et al Jan. 14, 1941 Von Fuchs et a1 May 5, 1942 Blanding Nov. 24, 1953 

1. A COMBINATION PROCESS FOR PRODUCING LUBRICATING OIL COMPRISING THE STEPS OF CATALYTICALLY CRACKING A GAS OIL BOILING WITHIN THE RANGE OF ABOUT 650* TO 1100*F., SEGREGATING A FIRST OIL FRACTION BOILING WITHIN THE RANGE OF ABOUT 650* TO 110*F. FROM THE CRACKED PRODUCTS, SEGREGATING A SECOND OIL FRACTION BOILING WITHIN THE RANGE OF ABOUT 650* TO 1100*F. FROM A PARAFFIN CRUDE OIL, AND CONTACTING A MIXTURE OF SAID FIRST AND SECOND OIL FRACTIONS WITH A SELECTIVE SOLVENT FOR AROMATIC COMPOUNDS TO REMOVE AROMATIC COMPOUNDS FROM THE SAID MIXTURE, SAID MIXTURE CONTAINING ABOUT 50% OF SAID FIRST OIL FRACTION, 